The invention relates generally to the methods and apparatus for separating hydrous slurries into two or more fractions through collision scrubbing. High velocities are created for attrition collisions to facilitate particle separation.
Various methods and apparatus have been used to separate slurries containing solids into several fractions to aid in extraction of the target mineral. Many sizing and classifying methods employ gravity separation, the separation being dependent on the difference in the settling rates or settling velocities of the particles in a relatively quiescent body of water. The different settling velocities of the solid particles of the slurry may be by virtue of particles differing in size, particles of different substances differing in their densities, or both.
Methods and apparatus of this type are subject to certain disadvantages and limitations. For example, the separation may not be as sharp as desired, particularly for certain types of slurries. The sharpness of separation tends to be subject to variations, which generally occur when there are changes in the solids content of the feed or in the relative amounts of the solids in the feed having different settling velocities. Also, the apparatus may be excessively elaborate in structural detail and size for the capacity or sharpness of separation desired. For a given processing capacity, the size of such equipment is relatively large.
Beyond gravity separation, other means of separating mineral ore involve various mechanical and chemical processes. Mechanical processes include: rotary scrubbers, which roll and tumble rock in water; log washers, which have paddles to scrub and transport the material from one point to another; pebble attrition or autogenous mills, which are rotary turning barrels that tumble the rock and particles in water and pass the same on to the next process; wet vibrating screens, which hydrate the material during agitation; high speed paddle blenders, which are batch mixes and not suited for continuous flow; and pulverization.
The disadvantages to these processes include the rate at which ore can be processed and the expense. Alluvial ore deposits require thousands of tons of raw material to be mined, processed, and refined daily. The current methods and apparatus either cannot efficiently process the large amounts necessary in mining or are cost prohibitive.
An object of the invention is to improve upon hydraulic separating methods and apparatus, particularly with respect to providing an efficient and economical means to separate mineral ore at a desired sharpness of separation.
Another object of the invention is to provide an apparatus that is relatively simple in construction and operation, which provides for changes in the character and rate of feed slurry.
When alluvial or placer deposits of ore are mined, large amounts of unwanted material surround the target mineral. For example, gold particles or granules are encased in the local variety of clay. In many types of such ore processing, it is customary to add water to the ore mixture to produce a slurry that facilitates mechanical processing. The present invention is an efficient way of dislodging the unwanted material from the target mineral carried in the slurry. The invention also permits changes in the flow rate and viscosity of the slurry mixture using a simple and economical apparatus. The flow rate of the slurry mixture can be adjusted to accommodate different particle sizes and varying viscosity and to promote effective scrubbing of mineral-bearing ore.
In one embodiment of the invention, a hydrous slurry mixture of the ore is pumped via hydrostatic and other pressure at a continuous flow rate into a receiving cylinder. Then, the mixture is pumped through two small openings on opposite walls of a hollow tube inserted into the receiving cylinder. These openings are positioned so that a jet of slurry flows from each hole and the jets collide in the center of the tube. This collision occurs at atmospheric pressure and causes clay and other particles to be dislodged from the mineral ore. The flow into the tube is controlled by the size of the nozzle, and the incoming pressure which may be adjusted to the required velocity for the collision. The dislodged material and scrubbed particles then fall out of the tube for further processing.